In a communication system, data transmission between access point and multiple stations has to be controlled to avoid conflicts between multiple concurrent transmissions. In general, this control is addressed through the medium access control (MAC) layer of a communication protocol.
A kind of MAC layer transmission control technology is called as Distributed Coordination Function (DCF), which employs a carrier sense multiple access/collision avoid (CSMA/CA) distributed algorithm. In some wireless systems using DCF, a wireless device that has data to transmit first listens to the medium to detect whether any other wireless device is currently transmitting. If another device is already transmitting, the original wireless device will not begin transmitting. However, if the device does not detect any other wireless device transmitting, the device will begin its own transmission.
Another transmission control technology is called as Point Coordination Function (PCF), which controls access to the medium using the infrastructure network configuration. In an infrastructure network configuration, an access point controls a basic service set and provides a connection to a larger network. To implement the PCF, an access point takes control of the medium in response to polling the connected stations.
Recently, the high potential provided by wire-line broadband access technology in bidirectional data transmission has been fully recognized, and more and more wire-line network technology has been developed and utilized. A kind of cost-effective bi-directional data transmission solution over the existing coaxial cable access network is called as ADoC (Asymmetric Data over Coaxial Cable) system. Since the signal transmission environment and network architecture for the ADoC system is quite different with that in wireless scenario, the conventional MAC layer mechanism DCF or PCF does not enjoy an acceptable performance.